Fuel Economy, Coming Right Up!

The main feature that I am excited about in the new 2011 Chevrolet Silverado HD Duramax LML is not the exhaust brake, not the trailer sway control or hill start assist, not the new body style, or even the USB connectivity, mobile WiFi or Bluetooth. Don't get me wrong, those are all great features. What is truly going to make this truck far more usable than the LMM generation is the selective catalyst reduction (SCR) system. Now this does add complexity to the exhaust system with another series of emissions components. And yes, the extra complexity can create more possibilities for failure. In general, we can always expect some teething problems when a newly designed vehicle is initially produced. But the SCR system buys for us one critical feature: fuel economy.

Bill Heath plans to return to Bonneville in 2010 with his 6.5L GM Diesel Racer. Some things just keep getting better with age.

The Heath Diesel land speed race team has raised its sites for the 2010 Bonneville Salt Flats events, hoping to top 160 MPH this season. Team 6265 has its goals set on wringing every last bit of speed from the current, nearly-stock engine configuration: this year’s effort represents a further refinement on the package but we still consider it Phase One. When we feel that we have gotten all we can from the truck in its current form, then we will move to Phase Two, which will include some changes in the fuel injection system. For now though, efforts are focused on making the best showing they can with the truck as it is.

Since 1994, GM diesel engines have used electronic engine controls to monitor and provide more precise diesel fuel injection. In the 16 years that have passed since then, diesel engine fuel injection strategies have advanced dramatically. This has enabled manufacturers to nearly double performance output and still reduce overall emissions. A whole new approach to diesel fuel injection was introduced by the first Duramax in 2001 (Ford had introduced electronic common rail diesel fuel injection before that, however the system required engine oil pressure to actuate the injectors. The fuel system used on the first Duramax was strictly electronically actuated and, as a result, far more precise). The Bosch common rail direct fuel injection system was new to the North American market at the time and provided speed and precision that had not previously been available. These factors, among others, allowed the Duramax engine to set the high-water mark for diesel engine power output. The 2001 Duramax engine rated at 300 HP and 520 foot-pounds of torque. Power output has increased incrementally to the current 365 HP and 660 foot-pounds of torque in the LMM Duramax.